Just remove their brains and they'll be fine
By Nanyang Technological University
Psychopaths, or individuals who display psychopathic traits,
tend to show a combination of self-centeredness, emotional coldness, and a lack
of empathy or remorse. In some cases, these characteristics are accompanied by
antisocial or criminal behavior.
The striatum, part of the brain’s subcortical forebrain
region, is involved in functions such as motivation, decision-making, and
reward processing. It also helps coordinate motor actions and plays a role in
how people plan and respond to stimuli.
The Striatum’s Role in Psychopathic Behavior
Previous studies have suggested that psychopaths may have an
overactive striatum, but the effect of its size on behavior had not been
confirmed until now. The new research provides evidence of a measurable
biological distinction between people with and without psychopathic tendencies.
While not every person with psychopathic traits engages in
crime, and not every criminal meets the definition of a psychopath, the two
groups show considerable overlap. Research has also consistently linked
psychopathy to aggressive and impulsive behavior.
To better understand these biological factors, researchers
examined MRI scans of 120 adults in the United States. Participants were also
evaluated using the Psychopathy Checklist-Revised, a standard tool for
identifying psychopathic characteristics.
Assistant Professor Olivia Choy, a neurocriminologist from
NTU’s School of Social Sciences and co-author of the study, explained, “Our
study’s results help advance our knowledge about what underlies antisocial
behavior such as psychopathy. We find that in addition to social environmental
influences, it is important to consider that there can be differences in
biology, in this case, the size of brain structures, between antisocial and
non-antisocial individuals.”
A Developmental and Genetic Perspective
Professor Adrian Raine from the Departments of Criminology,
Psychiatry, and Psychology at the University of Pennsylvania, who co-authored
the study, stated “Because biological traits, such as the size of one’s
striatum, can be inherited to a child from a parent, these findings give added
support to neurodevelopmental perspectives of psychopathy – that the brains of
these offenders do not develop normally throughout childhood and adolescence.”
Professor Robert Schug from the School of Criminology,
Criminal Justice, and Emergency Management at California State University, Long
Beach, who co-authored the study, added “The use of the Psychopathy
Checklist-Revised in a community sample remains a novel scientific approach:
Helping us understand psychopathic traits in individuals who are not in jails
and prisons, but rather in those who walk among us each day.”
Highlighting the significance of the work done by the joint
research team, Associate Professor Andrea Glenn from the Department of
Psychology of The University of Alabama, who is not involved in the research,
stated “By replicating and extending prior work, this study increases our
confidence that psychopathy is associated with structural differences in the
striatum, a brain region that is important in a variety of processes important
for cognitive and social functioning. Future studies will be needed to understand
the factors that may contribute to these structural differences.”
The results of the study were published in the Journal
of Psychiatric Research.
Bigger Striatum, Greater Need for Stimulation
The analysis of MRI scans and interview data revealed that
people with larger striatums were more likely to exhibit impulsivity and a
stronger desire for excitement or risk-taking behavior.
The striatum is part of the basal ganglia, a cluster of
neurons located deep within the brain. The basal ganglia receive input from the
cerebral cortex, which governs reasoning, social behavior, and decision-making
about which sensory information deserves attention.
Over the past two decades, scientists have expanded their
understanding of the striatum’s role, finding that it may also be linked to
social and behavioral regulation. However, until now, few studies had examined
whether these structural differences appeared in women as well as men.
Brain Differences Found in Both Men and Women
Within their group of 120 participants, the researchers
identified 12 women and found, for the first time, that enlarged striatums were
associated with psychopathic traits in both males and females. Normally, the
striatum shrinks as the brain matures from childhood into adulthood, suggesting
that psychopathy could be tied to differences in brain development.
Asst Prof Choy suggested “A better understanding of the
striatum’s development is still needed. Many factors are likely involved in why
one individual is more likely to have psychopathic traits than another
individual. Psychopathy can be linked to a structural abnormality in the brain
that may be developmental in nature. At the same time, it is important to
acknowledge that the environment can also have effects on the structure of the
striatum.”
Prof Raine added, “We have always known that psychopaths go
to extreme lengths to seek out rewards, including criminal activities that
involve property, sex, and drugs. We are now finding out a neurobiological
underpinning of this impulsive and stimulating behavior in the form of
enlargement to the striatum, a key brain area involved in rewards.
The research team plans to continue investigating why some
individuals develop this enlargement of the striatum and how it contributes to
psychopathic traits.
Reference: “Larger striatal volume is associated with
increased adult psychopathy” by Olivia Choy, Adrian Raine and Robert Schug, 6
March 2022, Journal of Psychiatric Research.
DOI:
10.1016/j.jpsychires.2022.03.006
A version of this article was originally published in
June 2022.
